Radio signaling system



Nov. 24, 1936. n. A.- F'Qx RADIO SIGNALING SYSTEM 3 Sheets-Sheet 1 Filed July 5l, 1833 Nov. 24, 1936. R, A, FOX

u RADIO SIGNALING SYSTEM Filedv Jlily 3l, 1933 3 Sheets-Sheet 2 A TTU/PNEYS.

Novi 24, 1936. R. A.' Fox RADIO SIGNALINQ SYSTEM 3 Sheets-Sheet 3 v Nmx A P Afro/Mfrs.

Patented Nov. y24, 1936 lUNI-rizo STATES 'PATENT OFFICE l 2,061,699 RADIO SIGNALING SYSTEM Robert A. Fox, Lorain, Ohio, will!!! to The Lorain Telephone Company, Lorain, Ohio, a

vcorporation of Ohio Application .my 31, 193s, serial No. 982,9"19V 18 Claims.

cluded from receiving an intelligible version of f the messagesbeing exchanged.

Another object is to provide such a radio signaling system wherein all the remaining stations are rendered inoperative, both as to transmitting and receiving, except for the reception of a busy signal, until the interchange of messages between the master station and the working subsidiary station has been concluded.

Another object is to provide such a radio signaling system wherein indicating means are provided to show the remaining stations that the .master station is already in communication with another subsidiary station.

Another object is to provide such a radio signaling system wherein the master receiving station is provided with means for joining wired' telephone lines thereto, to permit the direct transfer of radio telephone messages to wired telephone lines and systems. r

Another'object is to provide a radio signaling system wherein a radio transmitter is automatically brought into operative condition when the transmitter mouth piece is raised from its rest, and automatically made inoperative when replaced on its rest. i

Another object is to provide a radio signaling system wherein the signals sent out between the master station and a subsidiary station operate busy tone devices in the remaining subsidiary stations.

Another object is to provide a radio signaling system wherein thebusy tone is made of such character not only to warn' the station that another station is already working, but also to interfere with the actual message to such an extent as to prevent its intelligible reception.

Another object -is to provide a radio signaling system having devices for rendering the busy tone device inoperative if itis not alreay in operation when the operator raises the transmitter mouth piece from its rest.

Another object is to provide such a radio signaling system having means for alternately rendering leither the radio transmitter or the radio receiver inoperative when one of them is in use.

Another object is to provide a radio signaling system having means to operate a warning signal to call the operator's attention to the presence of a signal, yet having means incorporated therewith to render the signal audible as a call signal yet unintelligible as a message signal.

Another object is to provide a radio signaling system wherein means are provided so that a voice speaking into the transmitter mouth piece causes the transmitter circuit to be automatically closed and the receiving circuit automatically locked out of use.

Another object is to provide a radio signaling system combining radio telephone and wired telephone systems wherein the reception of vocally-modulated radio signal waves operates warning signals, the warning signal circuit beling automatically locked in closed circuit position until the operator heeds the signals and properly connects the wired telephone lines to the radio set.

In the drawings:

Figure lisa diagrammatic representation of the circuit employed in a subsidiary station, arranged according to one form of my invention.

Figure 2 is a diagrammatic representation of the circuit employed in the locking device.

Figure 3 is a diagrammatic representation of the circuit employed in the master station, arranged according to my invention.

Figure 4 is a diagrammatic representation of a radio-transmitting circuit showing how and where a lockout switch may be placed in accordance with my invention.

Arrangement of subsidiary station Referring to the drawings in detail, Figure 1 shows the arrangement of a combined receiving and transmitting circuit in a subsidiary station, according to my invention. It will be understood that the master station and the subsidiary stations may be located entirely on land, entirely on the sea, or partly on land and partly on the sea or in the air. The arrangement of a master station on land and subsidiary stations on ships at sea is chosen as a convenient illustrative arrangement.

In Figure 1, the subsidiary station is shown as possessing a radio receiver l of any suitable type, having a receiving antenna 2' and a ground connection 3. The plate circuit of one of the vacuum tubes in the radio receiver I has leads which are brought out through the lines 4 and 5 to the operating coil of a relay 6 placed in series therewith (Figure l). The grid of this vacuum tube is biased to such a point that no plate current will flow in the absence of radio signal waves; that is, that the presence of radio frequency input voltage is necessary to be applied to the grid of this vacuum tube from the radio frequency amplifier circuit of the radio receiver I in order to upset this grid bias and cause a iiow of plate current to take place.

The relay 6, when thus energized, closes the normally-open switch 1. The latter joins the power line 8 with the power line 9 through the normally-closed switch I0 of the relay II by way of the operating coil of the relay I2 (Figure 1). When the operating coil of the relay I2 is thus energized by the energization of the relay 6, it opens its normally-closed switch I3 which otherwise connects the operating coils of the relays II and I4 to the power lines 8 and 9 by way of the hook switch I5. The latter is kept normally open by the action of the hook switch plunger I6 which is pressed downward by the weight of the hand telephone I1. When the hand telephone I1 is raised, the plunger I6 rises under the influence of its coil spring I8, allowing the switch I5 to close and thus close the circuit energizing the operating coils of the relays I I and I4 when the switch I3 remains in its normallyclosed position, as it does when the operating coil of the relay I2 remains unenergized.

The relay II also contains and actuates the normally-open switch I9 placed in series with the power line 9 shortly before the latter enters the converter 29, and beyond its connection with the line energizing the operating coils of the re lays 6, II, I2 and I4.

When the switch I9 is closed by the energization of the relay II, power current of the direct or continuous type is admitted to the converter 20 from the power lines 8 and 9 leading from the ships generator lines 2| and 22 or from the ships emergency battery lines 23 and 24. Whether the generator lines 2| and 22 or the battery lines 23 and 24 shall furnish current to the power lines 8 and 9 is controlled by the relay, whose operating coil is connected between the generator lines 2| and 22 through the double-throw relay switches 26 and 21. When the ships generators are supplying current at a normal voltage, the operating coil of the relay 25 is energized to such an extent that the movableblades of the switches 26 and 21 are pulled toward the relay coil, thus causing current to be supplied to the power lines 8 and 9 by the generator lines 2I and 22 respectively. If, however, the ships generator voltage drops below a predetermined amount, as in the case of generator failure, the coil of the relay 25 is not sufficiently energized to hold the plates of its double-pole switches toward it (as in Figure l) and releases them, causing current to be thenceforth supplied from the battery lines 23 and 24 instead of from the generator lines 2I and 22.

The relay I2 also actuates the switch 28 which 'in turn operates the busy tone signaling device 29 which is likewise energized from the power lines 8 and 9. The busy tone signaling device 29 transmits its signals along the lines 30 and 3l through the band pass iilter 32 to the ear phone 33 of the hand telephone I1. The band pass filter 32 is of such nature as to lter off all frequencies above and below those necessary for the transmission of speech such as, for example, below 200 and above 3000 kilocycles. This prevents any energy from reaching the ear phone 33 that will create noise or interference with the reception of voice frequencies.

The busy tone 'signaling device 29 is likewise connected to one pole each of the double-throw relay switches 34 and 35 which are actuated by the relay I4. The opposite poles of the relay switches 34 and 35 are connected through the low-pass filter 36 to the signaling device 31. The latter may be of the loud speaker type or else may consist of a bell or buzzer. When a bell or buzzer is used at 31, the low-pass filter 36 becomes unnecessary. When a loud speaker is employed, however, the low-pass filter 36 removes all frequencies that are required for intelligible speech, but passes a band of frequencies sufficient to cause a signaling tone in the loud speaker at 31. In their normal positions with the operating coil of the relay I4 unenergized, the switches 34 and 35 connect the output lines 38 and 39 of the radio receiver I to the signaling device 31. If, however, the relay I4 is energized, its switches 34 and 35 are thrown to the opposite poles connecting the audio output of the radio receiver I to the telephone receiver 33 and busy tone 29.

The hand telephone i1 contains a telephone transmitter 48 of any suitable type, such as a microphone type, connected by the lines 4I and 42 to the radio transmitter 43 of the subsidiary station. The radio transmitter 43 has its transmitting antenna 44 and ground connection 45. The transmitter 43 is controlled by the hook switch 46 which is likewise actuated by the plunger I6 of the hand telephone I1 in the same manner as the hook switch I5 previously described. Accordingly, when the hand telephone I1 is raised from its rest, the hook switch 46 is closed, placing the radio transmitter 43 in an operative condition, provided that the other relay switches are properly closed.

The direct or continuous current from the power lines 8 and 9 passes through the converter 20 and therein becomes alternating current; this proceeds by the lines 41 and 48 into the transmitter 43.

A locking device 49 is provided whereby the radio receiver I is automatically rendered in' operative when the radio transmitter 43 is used or vice versa, for safety purposes. The input lines 50 and 5I of the locking device 49 are connected to the lines 4I and 42 leading from the hand telephone transmitter 4D to the radio transmitter 43 (Figure 1). The output lines 52 and 53 from the locking device 49 lead to the operating coil of a relay 54 in series therewith. The relay 54 controls a pair of normally-open relay switches 55 and 56. The relay switch 55, when closed by the energization of the relay 54, directly connects the receiving antenna 2 to the receiving ground 3 through the lines 51 and 58,

thus rendering the radio receiver I inoperative at that time. The closing of the relay switch 56 by the same means closes the circuit between the lines 59 and 60 (Figures l and 4). The radio transmitter 43 (Figures 1 and 4) is of anytype suitable for the particular conditions encountered. Figure 4 shows a conventional transmitting circuit, and is illustrated in detail merely to show where the switch 56 of the relay 54 may be placed in order to control the operation of the radio transmitter 43. The major parts of the transmitting circuit are the microphone mouth piece transmitter 40, the master oscillator vacuum tubeA 18 and the modulated amplifier vacuum tube 19. The rectifier 80 converts the alternating current from the lines 41 and 48 into the various direct currentfvoltage necessary for the operation of the circuit. The output lines of the radio transmitter are connected respectively to the transmitting antenna H 44 and the ground connection 45.

Thus the energization of the operating coil of the relay 54 closes the switch 56 which permits current to iiow from the rectifier 80 to the balance of the circuit, placing the radio ter being chosen merely for illustrative purposes.

Locking device circuit 'Ihe circuit contained within the locking device 49 is shown in Figure 2. The lines 59 and 5| leading i'rom the. transmitter mouth piece lines 4| and 42 respectively are connected to the 'primary winding oi' the transformer 6|. The secondary lead .62 thereof is connected to the grid and plate of the rectii'ying vacuum tube 63, the other secondary lead 64.and the line leading from the electron discharge member of the vacuum tube 63 are interconnected by the fixed condenser 66 and the resistance 61. Beyond these the line 64 leads to the minus terminal of the C battery 66, thus providing a bias for the grid of the rectifying tube 63. The positive pole of the C battery 68 and the negative pole of the B battery 69 are grounded as at 19, and the positive pole of the B battery 69 is connected to the output line 53.

Beyond the resistance 61, the line 65 is connectc'd to the grid 1 of the relay control vacuum tube 12, the plate 13 of which is connected to the output line 52.

'I'he laments of the vacuum tubes 63 and 12 are lighted by current from transformers 14 and 15 communicating with the power lines of the circuit. The electron discharge element 16 of the relay control vacuum tube 12 is grounded, as at 11. The output lines 52 and 53 oi the locking device 49 may be connected to any suitable apparatus, such as to the operating coil of the relay 54 (Figure 1).

Arrangement of master station The master station (Figure 3) contains a master radio receiver 8| whose input lines are connected to a receiving antenna 82 and ground 83 respectively. The output linesv 84 and 85 from the master radio receiver 8| are connected to the master wired-telephone central switchboard 86 of any suitable type. 'Ihe central switchboard 86 is connected to the wired-telephone lines 81 and 89, whereby the radio telephone messages intercepted by the master radio receiver 8| may be transferred' directly to the wired-telephone system and thence to any telephone subscriber. The master wired-telephone central -switchboard 86 is likewise connected by the lines 89 and 99 to the operating coil of a relay 9| having paired switches 92 and 93 operated simultaneously by the energization of the operating coil of the relay 9|, which occurs when the switchboard operator at the master central switchboard 86 manually plugs in the call coming from the master radio receiver 8|. The closing of the normally-open switch 92 places the master radio transmitter 94 in an operative lcondition by closing the circuit between the (Figure 3).

nected to the master radio transmitter by the 'leading from the master switchboard 66 to the 3 meal operator of the master station that the master radio transmitter 94 is now in circuit and ready for use.

The master radio receiver is similarly connected to the locking device-98 through the lines 89 and |99, in a manner analogous to that already described for the subsidiary radio receiver and locking device 49. The two locking devices 49 and 98 are of similar construction and arrangement. The output lines |9| and |92 of the locking device 98 are connected to the operating coll `of a. relay |93. The latter, when energized, closes the normally-paired switches |94 and |95, the former operating a warning signal |96, here shown as a red lamp bulb. The-red bulb |96 serves to warn the radio technical .operator that signals are being received by the master radio receiver 82 so that he may have the master radio transmitting circuit in readiness for immediate operation when the switchboard operator plugs in the call on the master central switchboard 86. The switch when closed by the energization of the relay |93 operates the warning signal |91, here shown as a lamp bulb of any suitable color. 'I'he warning signal |91 is placed near the master central switchboard 86 to warn the operator thereof that signals are being received by the master radio receiver 9|.

The relay |93 is of the lock-up type. The latching action thereof is accomplished by any suitable means, the means shown diagrammatically in Figure 3 being a lever |98 urged into latching engagement with the paired switches |94-|95 by the coil 'spring |99 and pivotally mounted as vat ||9. When the energization ofthe relay |93 pulls the 'paired switch arms of the switches |94 and 95 downward, the latching lever |98 slips into position and prevents the re turn thereof. 'Ihis-holds the switches |94 and |95 in closed circuits and thus operates the warning signals |96 and |91 continuously.

The signal input circuit inFigure 3 includes a hybrid circuit ||5 with an artificial balancing line ||6 connected thereto by the lines ||1 and H8. 'I'he hybrid circuit itself is connected to the master radio receiver'8l by the lines 84 and 85, and is connected to the master wired telephone central switchboard 86 by the lines ||9 and |29 The hybrid circuit finally is consignal input lines '|2l and |22.

The master central switchboard 86 includes a cord circuit |23 connected to a battery, or other source of current |24, by the line |25. .The lines |9 and |20 are interconnected with the line 89 through the jack switch |26. The lines 61 and 88 are connected to one another and to the supervision line |21 by the jack |28. The line 99,

relay 9|, is grounded by means of the line |29, and the opposite side of the battery |24 is grounded by the line |39.

When the switchboard operator at the master central switchboard 86 heedsthe warning and connects the switchboard so that it energizes the relay 9|, the latter attracts the portion of the latching leverv |98, moving the whole and unlatching the paired switches |94 and |95, thus disconnecting the warning signals |96 and |91.

Upon the completion of a manual connection by the telephone operator at the master central switchboard 86, through the operation of the cordcircuit |23, the relay 9| is energized and applies power to the transmitter in the manner described in more detail b elow. While an interchange of messages is taking place, however, the hybrid circuit I I transmits speech from the wired telephone lines 81 and 88 to the transmitter. When speech is fed from the master radio receiver 8I to the hybrid circuit II5 it is transmitted to the wired telephone lines 81 and 88, but is balanced out and not transmittedby the lines I2I and |22 to the master .radio transmitter 84.

Operation in subsidiary station communication with master station Let it rst be assumed that none of thesubsidiary stations is in communication with the master, station, and that the particular radio channel is clear, to which these stations are tuned. Let it also be assumed that one of the subsidiary stations is to place a call to the master station at this time when the channel is noty the relay II opens its normally-closed relay` switch I0, thus preventing the energization of the relay I2. The latter is thus henceforth unable to open the normally-closed switch I3 and thus interfere with the operation of the radio transmitter 43. The relay I2 is also thereby prevented from closing the switch 28 and operating the busy tone signaling device 29. Meanwhile the energization of the relay I4 simultaneously with that of the relay II shifts the relay switches 34 and 35, thereby connecting the audio output lines 38 and 39 from the radio receiver I to the telephone hand set ear phone 33 and disconnecting them from the signaling device 31.

After lifting the telephone hand set I1 from its cradle, the operator listens for the busy tone: hearing none, he calls the master station with 4such pre-arranged signals as have been previously decided upon. As soon as the current variations set up in the lines 4I and 42 by the action of the voice upon the microphone in the hand set transmitter 40 reach the locking device 49 by way of the lines 50 and 5I, the latter pass through the transformer 6I (Figure 2) and through the rectifying tube 65. The direct current emerging from the rectifying tube 65 charges the condenser 66. Before any current variations due to speech came into the circuit, the condenser 66 discharged through the resistance 61 without any effect upon the system, hence the relay 54 remained unenergized and its switches 55 and 56 consequently open. The current variations from the speech, however, impose an additional charge upon the condenser 66 which upsets the grid bias of the C battery 68 on the grid 1I of the relay control vacuum tube 12, thus giving rise to a flow tive condition by connecting the lines 59 and 80 within the radio transmitter 43 (Figure 4) The condenser 66 of the locking device 43 (Figure 2) is of suiilcient capacity to accumulate an adequate charge which operates to keep the relay 54 energized between words, and its switches 55 and 58 consequently closed` If, however, there is a greater pause than normal between words, the condenser 66 becomes completely discharged and the relay 54 de-energized, thus opening its switches 55 and 56. This action disconnects the receiving antenna 2 from its by-pass connection through the lines 51 and 58 to the ground 3 and places the radio receiver I in an operative condition (Figure 1). The same action opening the relay switch, 56 of the relay 54 breaks the circuit of the radio transmitter 43 and places the latter in an inoperative condition.

Having called the master station, the operator listens in the ear phone 33 for the answering call of the master station. When this call comes in over the receiving antenna 2, its waves are amplied by the initial radio frequency stages of the radio receiver I, and thus amplified upset the grid bias of the vacuum tube to which the leads 4 and 5 are connected, thus causing plate current to ow through them into the operating coil of the relay 6, energizing it and closing the normallyopen relay switch 1. The relay switch IIJ of the relay II still remains open, however, from the energization of the latter, hence the busy ltone signaling device 29 canot operate. The message thus passes from the output lines 38 and 39 of the radio receiver through the switches 34 and 35 to the head set ear phone 33 and is heard by the operator. Messages can thus be interchanged between the operator and the master station, the transmitter being at once connected and the radio receiver disconnected whenever the operator talks into the hand set transmitter microphone 40, by reason of the action of the locking device 49 previously described.

Operation in attempted interruption by second subsidiary station While the above interchange of messages is taking place between one of the subsidiary stations and the master station, let it be assumed that another subsidiary station desires to send a message to the master station: the second subsidiary station operator raises his hand set I1 and listens for the busy tone. Meanwhile the signals from the two intercommunicating stations come in over the receiving antenna 2 of the second subsidiary station, which is a duplicate of the circuit shown in Figure 1. This time the radio signals have energized the operating coil of the relay 6 in the manner previously described, and the current has passed through the normallyopen relay switch 1 closed thereby through the normally-closed relay switch I0 to and through the operating coil of the relay I2, the relay II having not yet been energized.

The energization of the relay I2 in this way opens the normally-closed switch I3, thus preventing subsequent energization of the relays II and I4, and at the same time closing the normally-open relay switch 28. The latter sets the busy tone signaling device in operation, creating an audible tone in the ear phone 33. This tone not only warns the second subsidiary station operator that another subsidiary station is already using the radio channel, but also assists in preventing intelligible reception of the messages by sound by the other station. The continued deenergization of the relay 4 leaves its switches 34 and 35 in the position shown in Figure 1, connectnot be able to understand their meaning.

By thus preventing the energization of the elay il and the consequent closing of its normally-open switch I9, the second subsidiary station transmitter 43 is thereby kept from receiving power currentr through the line 9, and is accordingly locked out of operation while the first subsidiary station is working, and at the same-time the busy tone signaling device 29 is locked in operation. The second subsidiary stationis thus warned that the channel is busy and also is prevented from attempting to transmit messages over the same channel until the line is free.

Operation in master station calling a particular subsidiary station.

Assuming that the above interchange of messages hasceased, let it now be assumed that the master station has 'a message for a particular subsidiaryv station. The master station places its radio transmitter 94 in operation and calls the subsidiary station by sending out a predetermined signal peculiar to that vsubsidiary station. As soon as it has transmitted this signal several times, it shuts off its transmitter and listens for the answer of the called station. The calling signal from the master station is received by all of the subsidiary stations since all of their receivers are tuned to the same wave length or frequency. When the signals from the master -station come in through the radio receiver I (Figure 1), they are amplified by the radio frequency and audio frequency circuits of the radio receiver and pass through the low-pass filter into the signaling device 31, where the call signal is made audible. The operatorlof the particular station called raises his telephone hand set |1 and thus locks in his own receiving and transmitting circuits and when the shore answers, it locks out the transmitting circuits of the other subsidiary stations and causes their busy tone signaling devices to operate in the manner previously described. thenceforth proceeds as before.

Operation in master radio station The master radio station (Figure 3) rec-elves the subsidiary station signals through the master radio receiver 8|, The signals pass through the output lines 99 and |00 into the locking device 98, which is arranged and operated in substantially the same way as the locking device 49 previously described. The signals cause the locking device 98 (Figure 3) to energize the operating coil of the relay |03 in a manner analogous to that described above for the relay 54 (Figure 1). Thus energized, the relay |03 closes the paired switches |04 and |05 (Figure 3), and the latching lever |08 slips in behind these switches and holds them-in a closed position. As a result of this, the warning light |01 'glows on the master central switchboard 88 and the red warn- The operation ing light |06 glows at the .technical operators.

while the switchboard operator 88 receives the call and plugs it in to the appropriate wired telephone lines` 81 and 88. As the switchboard operator plugs in the call, the same action causes the working coil of the relay 9|- to be energized, as previously described, closing the normallyopen switches 92 and 93 and withdrawing the latching device |08, allowing the switches |04 and |05 to open when the relay |03 is de-energized. The closing of the relay switch 92 places the master radio transmitter in an operative condition, and/the closing of the relay switch 93 operates 'the green warning signal 91lat the technical operators desk, notifying him that` the transmitter is about to be operated. The master radio transmitter 94 is then operated 4in the usual manner and the subsidiary station communicated with in the way described above.

In this manner the master radio station can communicate with any one of a plurality of subsidiary radio stations, and the others will be prevented, not only, from transmitting signals during the progress of the intercommunication, but will also be prevented from listening in on the conversation or reading the messages. In this way a measure of secrecy is accomplished. It will be obvious that the master radio station may likewise tune its receiver or another receiver and transmitter in the station to communicate with4 a different plurality of subsidiary stations in a manner substantially the same as that described above.

It will be understood that I desire to comprehend within my invention such modifications as may be necessary to adapt it to varying conditions and uses.

Having thus fully describedv my invention,`

controlled by the removal of the telephone receiver and transmitter, means controlled by said switch for connecting the radio transmitter to a source of sending power current, a radio receiver adapted to be brought in circuit with the telephone receiver upon the lifting thereof, a signaling device connected to the radio receiver, means upon the connecting of the radio receiver with the telephone receiver for rendering the signaling device inoperative, a busy tone device connected to the source of sending power current, the telephone receiver and the radio receiver, and means upon lifting the'receiver for preventing the operation of said busy tone device if it is not already in operation.

2. In combination, a telephone receiver and transmitter, a radio transmitter connected to the telephone transmitter, a telephone switch controlled by the removal of the telephone receiver and transmitter, means controlled by said switch for connecting the radio transmitter to a source of sending power current, a radio receiver adapted to be brought in 'circuit with the telephone receiver upon the lifting thereof, a signaling device connected to the radio receiver, means upon the connecting of the radio receiver with the telephone receiver for rendering the signaling'device inoperative, a busy tone device connectedA to the source of sending power current, the telephone. receiver and the radio receiver, means upon lifting the receiver 'for preventing the operation of said busy tone device if it is not already in operation, and means of alternately ren'- dering the radio transmitter and radio receiver inoperative when one of them is operating in the transmission or reception of signals.

3. In combination, a radio transmitter adapted to emit electro-magnetic Waves, a telephone transmitter connected to the radio transmitter, a telephone receiver, a telephone switch, a radio receiver adapted to receive electro-magnetic waves4 and connected to said telephone receiver, a busy tone device connected to the telephone receiver and the radio receiver, means set in operation by attempted reception of signals with said radio receiver for temporarily disabling said busy tone device, and means set in operation by the electro-magnetic waves from the prior operation of another radio transmitter for rendering said busy tone device operative to interfere with the intelligible reception of signals by said radio receiver.

4. In combination, a radio transmitter, means of applying and transmitting energy thereto, a telephone transmitter connected to the radio transmitter, a telephone receiver, a telephone switch, a radio receiver connected to the telephone receiver, a busy tone device connected to the telephone receiver and the .radio receiver, means for rendering said busy tone device inoperative, said parts being so arranged that when the telephone is put into circuit with the radio transmitter and receiver the busy tone device will be prevented from operating if not already operating yet will be permitted to continue operating if already operating whereby the telephone receiver will be prevented from receiving any other signals than the busy tone signals from the busy tone device, and means after the busy tone device is rendered inoperative for alternately rendering the radio transmitter and radio receiver inoperative when one or the other is operating during the period of voice transmission or reception respectively.

5. In combination, a radio transmitter, means of applying and transmitting energy thereto, a telephone transmitter connected to the radio transmitter, a telephone receiver, a telephone switch, a radio receiver connected to the telephone receiver, a busy tone device connected to the telephone receiver and the radio receiver, means for rendering said busy tone device connected to the telephone receiver and the radio receiver, means for rendering said busy tone device inoperative, said parts being so arranged that when the telephone is put into circuit-with the radio transmitter and receiver the busy tone device will be prevented from operating if not already operating yet will be permitted to continue operating if already operating whereby the telephone receiver from receiving any other signals than the busy tone signals from the busy tone device, means after the busy tone device is rendered inoperative for alternately rendering the radio transmitter and radio receiver inoperative when one or the other is operating during the period of voice transmission or reception respectively, means connected to the radio receiver for receiving call signals prior to the operation of the telephone receiver, and means for rendering the signaling device inoperative upon rendering the telephone receiver operative.

6. In combination, a telephone receiver and transmitter and telephone switch; a radio transmitter having a power supplying circuit and power switch; a power lconnecting relay, a radio receiver, a signaling device connected thereto, a signaling device switch for disconnecting the signaling device and connecting the radio receiver to the telephone receiver, a busy tone device connected tothe telephone receiver, to the radio receiver and tothe power circuit; a busy tone relay and switch for rendering the busy tone device inoperative or operative, and a conversion relay for rendering the switch device inoperative and connecting the radio receiver to the telephone receiver.

'7. In combination, a telephone receiver and transmitter and telephone switch; a radio transmitter having a power supplying circuit and power switch; a power connecting relay, a radio receiver, a` signaling device connected thereto, a signaling device switch for disconnecting the signaling device and connecting the radio receiver to the telephone receiver, a busy tone device connected to the telephone receiver, to the radio receiver and to the power circuit; a busy tone relay and switch for rendering the busy tone device inoperative or operative, a sensitive relay and switch for controlling the connecting of the busy tone device with the radio receiver, and a conversion relay for rendering the switch device inoperative and connecting the radio receiver to the telephone receiver.

8. In combination, a telephone receiver and transmitter and telephone switch; a radio transmitter having a power supplying circuit and power switch; a power connecting relay, a radio receiver, a signaling device connected thereto, a signaling device switch for disconnecting the signaling device and connecting the radio receiver to the telephone receiver, a busy tone device connected to the telephone receiver, to the radio receiver and to the power circuit; a busy tone relay and switch for rendering the busy tone device inoperative or operative, a sensitive relay and switch for controlling the connecting of the busy tone device with the radio receiver, a conversion relay for rendering the switch device inoperative and connecting the radio receiver to the telephone receiver, and a radio transmitter and receiver lock-out mechanism whereby when one is operating the other is rendered inoperative.

9. In combination, a telephone receiver and transmitter and telephone switch; a radio transmitter having a power supplying circuit and power switch; a power connecting relay, a radio receiver, a signaling device connected thereto, a signaling device switch for disconnecting the signaling device and connecting the radio receiver to the telephone receiver, a busy tone device connected to the telephone receiver, to the radio receiver and to the power circuit; a busy tone relay and switch for rendering the busy tone device inoperative or operative, a sensitive relay and switch for controlling the connecting of the busy tone device with the radio receiver, a conversion relay for rendering the switch device inoperative and connecting the radio receiver to the telephone receiver, a radio transmitter and receiver lock-out mechanism whereby when one is operating the other is rendered inoperative, a signaling device lter and a telephone receiver lter.

10. In combination in a radio telephone transmitting and receiving set, a radio telephone transmission circuit, a radio telephone receiving circuit, a busy tone circuit, means responsive to the attempted reception of signals to prevent the operation of said busy tone circuit, and means set in operation by the electro-magnetic waves from the prior operation of another radio transvmitting circuit for rendering said busy tone cirstations, and devices similarly responsive to indi-` ception of signalsby said first-mentioned radio receiving circuit whereby all other signals except' the busy tone signal will be made unintelligible by the action of said busy tone circuit.

11. In combination in a radio telephone transmitting and receiving set, a radio telephone transmission circuit, a radio telephone receiving circuit, a busy tone circuit, means responsive to the attempted reception of signals to prevent .the operation of said busy tone circuit, means set in operationv by the prior operation of another radio transmitting circuit for rendering said busy tone circuit operative to interfere with the intelligible reception of signals by said first-mentioned radio receiving circuit, whereby all other signals except the busy tone signal will be made unintelligible by the action of said busy tone circuit, and means associated with the receiver and transmitter and responsive to the operation of the one for locking the other temporarily out of operation whereby to prevent the accidental simultaneous operation of both receiver and transmitter.

12. In combination in a combined radio and wire system of communication, a master radio transmitter and receiver, a wire telephone terminal station connectible thereto and to wire telephone lines, a plurality of subsidiary radio transmitters and receivers associated therewith and tuned to substantially the same wave length as said master transmitter and receiver, and devices responsive to the prior operation of one subsidiary transmitter adapted to prevent the intelligible reception of signals by the other subsidiary stations.

13. Incombination in a combined radio and wire system of communication, a master radio transmitter and receiver, a wire telephone terminal station connectible thereto and to wire telephone lines, a plurality of subsidiary radio transmitters and receivers associated therewith and tuned to substantially the same wave length as said master transmitter and receiver, devices responsive to the prior operation of one subsidiary transmitter adapted to prevent the intelligible reception of signals by the other subsidiary cate the busy condition of the system to said other subsidiary stations.

14. In combination in a combined radio and wire system "of communication, a master radio transmitter and receiver, a wire telephone terminal station connectible thereto and to Wire telephone lines, a plurality of subsidiary radio transmitters and receivers associated therewith and tuned to substantially the same wave length as said master transmitter and receiver, devices responsive to the prior operation of one subsidiary transmitter adapted to prevent the intelligible reception of signals by the other subsidiary stations, devices similarly responsive to indicate the busy condition of the system to said other subsidiary stations, and means associated with each receiver and transmitter and responsive to the operation of the one for locking the other temporarily out of operation whereby to prevent the accidental simultaneous operation of both receiver and transmitter.

15. In combination in a combined radio and 'l0-wire system of communication, a master radio transmitter and receiver, a wire telephone terminal station connectible thereto and to wire telephone lines, a plurality of subsidiary radiol transmitters and receivers associated therewith".

and tuned to substantially the same wave length as said master transmitter and receiver, devices responsive to the prior operation of one subsidiary transmitter adapted to prevent the intelligible reception of signals by the other subsidiary stations, devices similarly responsive to indicate the busy condition of the system to said other subsidiary stations, means associated with each receiver and transmitter and responsive to the operation of the one for locking the other temporarily vout of operation whereby .y

to prevent the accidental simultaneous operation of both receiver and transmitter, a signaling device associated with each radio telephone receiver for indicating the presence of incoming signals to the operator While idle, and means for shutting ofi` the signaling device when the radio telephone receiver is put into operation for reception of signals.

16. In combination, a master radio-telephone transmitter and receiver', and a group of subsidiary radio-telephone transmitters and receivers tuned to substantially the same wave length as said master transmitter and receiver arranged for inter-communication by voicemodulated electro-magnetic waves; and means set in operation by the reception of the electromagnetic waves from the inter-communication between one subsidiary station and the master station for positively rendering the other subnetic waves from the inter-communication between one subsidiary station and the master station for positively rendering the other subsidiary transmitters inoperative, means'similarly set in operation to render the other subsidiary receivers incapable of reproducing intelligible signals, and means similarly set in op-` eration for indicating the busy condition of the system to said other subsidiary receivers.

18. In combination in a combined radio and wire system of communication, a master radio transmitter and receiver a wire telephone switchboard connectible thereto and to wire telephone lines, means set in operation by the closing and opening of the circuit between the master radio receiver and said switchboard for placing said master radio transmitter in an operative and inoperative condition respectively, a plurality of subsidiary radio telephone transmitters and receivers adapted to communicate with said master station, and means set in operation by the reception of the electro-magnetic waves from the intercommunication between one subsidiary station and the master station for positively rendering the other subsidiary transmitters temporarily inoperative and for renderingthe other subsidiary receivers temporarily incapable of reproducing intelligible signals.

ROBERT A. FOX.

CRRTIF/IVCATE op CORRECTION. Patent No. 2,061,699.- November 21;, 1956.

ROBERT A. Rox.

It is hereby certified that error appears in the printed specification ofthe above numbered patent requiring correction as follows: Page 6, first colmn, line 58, claim 5, after the word "receiver" insert --will be prevented; and that the said Letters Patent should be read with this correction therein that the same may conform 'to the record of the case in the Patent Office.

Signed and sealed this- 17th day of September, A. D. 1914.0.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents. 

